1. Field of the Invention
The current invention relates to a metal-sealing material-feedthrough. It further relates to usage as well as to a gas generator, airbag and belt tensioning device including an ignition device, comprehensively a metal-sealing material-feedthrough.
2. Description of the Related Art
Metal-sealing material feedthroughs are already known in various forms from the current state of the art. They are understood to be vacuum-tight seals of sealing materials, especially glass or synthetics to metal seals. In this type or arrangement the metals act as electrical conductors. We refer you to representative documentation U.S. Pat. No. 5,345,872, U.S. Pat. No. 3,274,937. Feedthroughs of this type are common in electronic and electrical engineering. The material used for sealing, especially glass, serves as an insulator. Typical metal-sealing material-feedthroughs are constructed such that metallic internal conductors are sealed into a pre-formed sintered glass component, wherein the sintered glass component or the glass tube is sealed into an outer metal component with the so-called base body. Preferred applications for metal-sealing material-feedthroughs of this type are for example ignition devices. One area of application is in airbags or belt tensioning devices in motor vehicles. In this instance the metal-sealing material-feedthroughs are a component part of an ignition device. In addition to the metal-sealing material-feedthrough, the entire ignition device includes an ignition bridge, the explosive agent, as well as a metal shrouding which tightly encloses the ignition mechanism. Either one or two, or more than two metallic pins may be inserted through the feedthrough. In one embodiment with one metallic pin the housing is grounded. In a two-pin embodiment one of the pins is grounded. The previously described ignition device is used especially for airbags or for belt tensioning devices in motor vehicles. Already known ignition devices of the aforementioned, or similar types are described in U.S. Pat. No. 6,274,252, U.S. Pat. No. 5,621,183, DE 29 04 174 A1, DE 199 27 233 A1, U.S. Pat. No. 5,732,634, U.S. Pat. No. 3,134,329, DE 34 14 625 A1 DE 34 15 625 A1, EP 1 225 415 A1, U.S. Pat. No. 3,971,320, EP 0 248 977 B1, US 2002/0069781 A1, DE 101 33 223 A1 as well as EP 1 491 848 A1 and EP 1 455 160 A1 whose disclosure contents are included in their entirety in the present application. The aforementioned ignition units include two metal pins. However, electronic ignition devices with a singular pin are also possible. The ignition devices which are known from the current state of the art include a metal base body or metal sleeve which is constructed as a pivoted component, or they include a base body of synthetic material. The metal base body has at least one feedthrough opening through which at least one metal pin is inserted. One fundamental problem in this embodiment is that this type of construction is material intensive and expensive. Also when constructed as a pivoted component the configuration of the pass through opening deviating from a circular cross section is possible only with additional costs. In addition, pivoted components are characterized by relatively large dimensions which is then reflected in a respectively necessary sizing of the entire ignition device.
Designs of ignition devices are known from EP 1 491 848 A1 which include a pair of electrodes arranged in an insulating material and a base body in the embodiment of a housing. In order to increase the resistance relative to the pressure created when the ignition is triggered and thereby in order to increase the ejection force, ways are provided on one of the components of the metal-sealing material feedthrough which interact with each other. These are provided either on the sealing material, the electrode or on the base body on the surface which is facing the neighboring element. The design on the base body includes at least one step, that is to say—a change in the cross section of the feedthrough opening wherein this causes an enlargement of the surface that is exposed to the pressure during the ignition process. There are no restrictions regarding the material choices for the base body so that, depending upon design, especially when constructed as a pivoted component, the already mentioned disadvantages also occur, which only intensify through the additional necessary inclusion of the required ways for the increase of the tensile force, extraction force, and/or ejection force.
A generic metal-sealing material-feedthrough is already known from EP 1 455 160 A1. This discloses a metal-sealing material-feedthrough which is described in a special design as a glass-to-metal-feedthrough, including one metallic base body through which at least one metal pin is inserted. If two metal pins are provided in a preferred design form then at least one of the two provides the ground connection to the base body at least indirectly, in other words, directly or indirectly through additional elements. In a design having two metal pins said metal pins are located parallel to each other. At least one of the metal pins is located in a feedthrough opening in the base body and is sealed relative to it through sealing material, such as in form of a glass slug. The base body is formed from a sheet metal element wherein in a first design form at least the feedthrough opening is created by a separation process, especially by punching. The base body itself is punched from a solid material. The final geometry of the base body however is achieved through a forming process, for example through deep-drawing. In a preferred design form the final geometry describing the outer contour and the basic geometry describing the feedthrough opening is produced at least by a separation process, especially punching. Final geometry means that no further forming processes will be conducted on this form. Basic geometry means that this either represents the final geometry if no further changes are required or that changes through ways of additional manufacturing processes, especially forming processes may be made, wherein the final geometry is achieved only following these additional processes. Ways are provided between the front and the back side in order to avoid a relative movement of sealing material in the direction toward the back relative to the inside circumference of the feedthrough opening, especially during ignition. The ways are an integral component of the base body or embody a structural unit with same. The manufacture of the base body by way of punching provides the advantage of short manufacturing periods and permits free forming, especially of the feedthrough opening. However, fabrication by way of punching is subject to limits with a view to individual material related parameters exceeding of which would render the fabrication uneconomical and which would also have a negative effect upon the available ejection force.
What is needed in the art is a metal-sealing material-feedthrough of the type mentioned at the beginning, including a base body which has at least one feedthrough opening which is obtained by punching and which is characterized by a high rigidity at low material- and labor expenditure and at the same time by high ejection forces. In addition, assembly errors which are a result of inaccurate coordination of the individual elements are to be avoided.